Nutritional Considerations

A two-year study led by John Reganold of Washington State University that provided side-by-side comparisons of organic and conventional strawberry farms has shown organic farms produced more flavorful and nutritious berries while promoting healthier and more genetically diverse soils. Published Sept. 1, 2010, in the peer-reviewed online journal PLoS One, the research study analyzed 31 chemical and biological soil properties, soil DNA, and the taste, nutrition and quality of three strawberry varieties on 13 convention and 13 organic commercial fields in California. The multi-disciplinary research team included expertise in agroecology, soil science, microbial ecology, genetics, pomology, food science, sensory science, and statistics. Findings in the paper showed organic strawberries had significantly higher antioxidant activity and concentrations of ascorbic acid and phenolic compounds, longer shelf life, and dry matter. In addition, the organic soils excelled in the areas of carbon sequestration, nitrogen, microbial biomass, enzyme activities, and micronutrients.

Researchers studying cultivation practices for high-bush blueberries in New Jersey found that blueberry fruit grown organically yielded significantly higher fructose and glucose levels, malic acid, total phenolics, total anthocyanins and antioxidant activity than fruit grown using conventional methods. Scientists carrying out the study are based at the U.S. Department of Agriculture’s Genetic Improvement of Fruits and Vegetables Laboratory in Beltsville, MD, and at Rutgers University in New Jersey.Source: Journal of Agricultural and Food Chemistry, Vol. 56, pages 5,788-5794 (2008), published online on July 1, 2008.

A report jointly produced by The Organic Center and professors from the University of Florida Department of Horticulture and Washington State University provides evidence that organic foods contain, on average, 25 percent higher concentration of 11 nutrients than their conventional counterparts. The report was based on estimated differences in nutrient levels across 236 comparisons of organically and conventionally grown foods. Source: “New Evidence Confirms the Nutritional Superiority of Plant-Based Organic Foods,” www.organic-center.org/reportfiles/5367_Nutrient_Content_SSR_FINAL_V2.pdf.

A study published in Environmental Health Perspectives showed that consuming organic products may lower children's exposure to potentially damaging pesticides. In the study, researchers at the School of Public Health and Community Medicine, University of Washington, recruited families at both a retail chain grocery store selling primarily conventional foods and at a local cooperative selling a large variety of organic foods in the Seattle, WA, metropolitan area. Parents were asked to keep a food diary for their children for three days, then the children's urine collected on day three was analyzed for pesticide metabolites. Children eating primarily organic diets had significantly lower levels organophosphorus (OP) pesticide metabolite concentrations than did children eating conventional diets. In fact, concentrations of dimethyl metabolites, one OP metabolite group, were approximately six times higher for the children eating conventional diets. Other studies indicate that chronic low-level exposure to OP pesticide may affect neurological functioning, neurodevelopment, and growth in children. "Dose estimates suggest that consumption of organic fruits, vegetables, and juice can reduce children's exposure levels from above to below the U.S. Environmental Protection Agency’s current guidelines, thereby shifting exposures from a range of uncertain risk to a range of negligible risk," authors Cynthia L. Curl, Richard A. Fenske, and Kai Elgethun wrote, adding, "Consumption of organic produce appears to provide a relatively simple way for parents to reduce their children's exposure to OP pesticides." A previous study by members of the study team had shown that children eating primarily organic diets had significantly lower OP pesticide exposure than did children consuming primarily conventional diets. In fact, an earlier study found no measurable pesticide metabolites in the urine of a child whose family bought exclusively organic produce. [Original study: Environmental Health Perspectives, Vol. 109, No. 3, March 2001 (pp. 299-303, C. Lu, D.E. Knutson, J. Fisker-Andersen, and R.A. Fenske, “Biological Monitoring Survey of Organophosphorus Pesticide Exposure among Preschool Children in the Seattle Metropolitan area”). Subsequent study: Environmental Health Perspectives ehponline.org, posted online Oct. 31, 2002, C.L. Curl, R.A. Fenske, and K. Elgethun, “Organophosphorus pesticide exposure of urban and suburban pre-school children with organic and conventional diets”].Source: Environmental Health Perspectives, March 2003.

A study has shown that organic soups sold commercially in the United Kingdom contain almost six times as much salicylic acid as non-organic soups. John Paterson, a biochemist at Dumfries and Galloway Royal Infirmary, and scientists at the University of Strathclyde in Scotland analyzed 11 brands of organic soup and compared their levels of salicylic acid with those in non-organic varieties. Salicylic acid, which is responsible for the anti-inflammatory action of aspirin, has been shown to help prevent hardening of the arteries and bowel cancer. The average level of salicylic acid in 11 brands of organic vegetable soup was 117 nanograms per gram, compared with 20 nanograms per gram in 24 types of non-organic soup. The highest level (1,040 nanograms per gram) was found in an organic carrot and coriander soup. Four of the conventional soups had no detectable levels of salicylic acid.Source: New Scientist magazine, March 16, 2002, page 10; European Journal of Nutrition, Vol. 40, page 289.

Research by visiting chemistry professor Theo Clark and undergraduate students at Truman State University in Missouri found organically grown oranges contained up to 30 percent more vitamin C than those grown conventionally. Reporting the findings at the June 2 Great Lakes Regional meeting of the American Chemical Society, Clark said he had expected the conventional oranges, which were much larger than the organic oranges, to have twice as much vitamin C as the organic versions. Instead, chemical isolation combined with nuclear magnetic resonance spectroscopy revealed the higher level in the organic oranges.Source: Science Daily Magazine, June 2, 2002.

Reviewing 41 published studies comparing the nutritional value of organically grown and conventionally grown fruits, vegetables, and grains, certified nutrition specialist Virginia Worthington concluded there were significantly more of several nutrients in organic crops. These included: 27% more vitamin C, 21.1% more iron, 29.3% more magnesium, and 13.6% more phosphorus. In addition, organic products had 15.1% less nitrates than their conventional counterparts. She also noted that five servings of organic vegetables (lettuce, spinach, carrots, potatoes and cabbage) provided the recommended daily intake of vitamin C for men and women, while their conventional counterparts did not. Worthington said the results are consistent with known soil dynamics and plant physiology.Source: “Nutritional Quality of Organic Versus Conventional Fruits, Vegetables, and Grains,” by Virginia Worthington, published in The Journal of Alternative and Complementary Medicine, Vol. 7, No. 2, 2001 (pp. 161-173).

A study commissioned by the Organic Retailers and Growers Association of Australia (ORGAA) found that conventionally grown fruit and vegetables purchased in supermarkets and other commercial retail outlets had ten times less mineral content than fruit and vegetables grown organically. For the study, tomatoes, beans, capsicums and silver beets grown on a certified organic farm using soil regenerative techniques were analyzed for mineral elements. The Australian Government Analytical Laboratory also analyzed a similar range of vegetables grown conventionally and purchased from a supermarket. A major flaw of the study, however, is that it compared fresh produce at the farm to produce in a supermarket. Thus, there could have been a difference in freshness, which could have affected the nutrients measured.Source: Organic Retailers and Growers Association of Australia, 2000, as cited in Pesticides and You, Vol. 20, No. 1, Spring 2000, News from Beyond Pesticides/National Coalition Against the Misuse of Pesticides.

A comparative study conducted by researchers at the Research Institute of Organic Agriculture (FiBL) in Switzerland found that organically grown apples were of higher quality than conventionally grown apples with respect to parameters that relate to health and taste (taste score, sugar-acidity-firmness index, nutritional fiber content, phenolic compounds content, and “vitality index” according to picture-grading methods for holistic quality assessment).Source: “Are organically grown apples tastier and healthier? A comparative field study using conventional and alternative methods to measure fruit quality,” F.P. Weibel, R.Bickel, S. Leuthold, and T. Alföldi), Acta Hort. 517: 417-427 (2000).

Organic produce has been found to be higher in antioxidants than its conventional counterparts.

Organic lemonade contains ten times more eriocitrin (an antioxidant) than a glass of its conventional counterpart, according to a recent study by Washington State University supported by The Organic Center. The study was the first-ever assessment of the bioavailability of three chiral flavonoids—hesperetin, naringenin, and eriocitrin—found in citrus fruits and juices. Organic lime juice had three times the level of eriocitrin compared to conventional lime juiceSource: Biopharmaceutics & Drug Disposition, Vol. 29, pp. 63-82, September 2007.

Research led by Alyson Mitchell at the University of California-Davis has shown that levels of flavonoids increase over time in crops grown in organically farmed fields. Study results found that organic tomatoes contain on average 79 and 97 percent more quercetin and kaempferol aglycones (beneficial flavonoids) that their conventionally grown counterparts. In the study, Mitchell and colleagues compared levels of key flavonoids in tomatoes harvested over a ten-year period from two matched fields—one farmed organically and the other with conventional methods including commercial fertilizers. Researchers analyzed organic and conventional tomatoes that had been dried and archived under identical conditions from 1994 to 2004. “The levels of flavonoids increased over time in samples from organic treatments, whereas the levels of flavonoids did not vary significantly in conventional treatments,” the report stated.Source: Journal of Agricultural and Food Chemistry, posted online June 23, 2007.

A research team at the University of California at Davis has found organic kiwi fruit had much higher levels of total polyphenol content than conventional kiwi fruit, resulting in higher antioxidant activity than their conventional counterparts. Study results also showed that organic kiwi fruit had higher levels of vitamin C. The kiwis studied were from nearby vineyards on the same farm in Marysville, CA.Source: March 27, 2007, online edition of the Journal of the Science of Food and Agriculture.

At the 2005 international congress Organic Farming, Food Quality and Human Health, Professor Carlo Leifert of Newcastle University reported findings that organically produced food had higher level of specific antioxidants and lower mycotoxin levels than conventional samples, and that grass-based organic cattle diets reduce the risk of E. coli contamination while grain-based conventional diets increase the risk.Source: http://www.qlif.org/.

Findings from a Danish showed organic vegetables have a higher concentration of natural antioxidants called flavonoids. The double-blind randomized, crossover study had two intervention periods, with test participants given organic food or conventional food for three weeks. Results were based on blood and urine samples tested. The study was conducted by The Institute of Food Safety and Nutrition under The Danish Veterinary and Food Administration, The Department of Human Nutrition and Centre for Advanced Food Studies under The Royal Veterinary and Agricultural University, and Risø National Laboratory.Source: Journal of Agricultural and Food Chemistry, Vol. 51, No. 19, 2003, pp. 5671-5676.

Organic fruits and vegetables show significantly higher levels of antioxidants than their conventionally grown counterparts, according to findings published by researchers at the University of California at Davis. In the study, researchers led by food scientist Alyson Mitchell compared the antioxidant levels in corn, strawberries and marionberries grown organically, sustainably (using fertilizer but no herbicides or pesticides) and conventionally. Antioxidant levels in sustainably grown corn were 58.5 percent higher than conventionally grown corn, while organically and sustainably grown marionberries had approximately 50 percent more antioxidants than conventionally grown berries. Sustainably and organically grown strawberries had about 19 percent more antioxidants than their conventional counterparts. The findings were published in the Feb. 26, 2003, print edition of the American Chemical Society peer-reviewed Journal of Agricultural and Food Chemistry. The study also showed sustainably grown and organic produce had more ascorbic acid, which the body converts to vitamin C.Source: “Comparison of the Total Phenolic and Ascorbic Content of Freeze-Dried and Air-Dried Marionberry, Strawberry, and Corn Grown Using Conventional, Organic, and Sustainable Agricultural Practices,” D.K. Asami, Y.-J. Hong, D.M. Barrett, and A.E. Mitchell, Journal of Agricultural and Food Chemistry, 51(5):1,237-1,241 (2003)

An Italian study has found organic pears, peaches and oranges had higher antioxidant levels than their conventional counterparts. The study was conducted by the Istituto nazionale di ricerca per gli alimenti e la nutrizione (National Institute of Food and Nutrition Research). In particular, researchers found that organic William's pears contain less fiber but more natural sugar, vitamin C and antioxidants compared to their conventional counterparts, and were more resistant to mildew and fungi. Organic Regina Bianca peaches, meanwhile, contain more antioxidants.Source: Journal of Agricultural and Food Chemistry. August 2002.

Organic cows grazing on fresh pasture produce milk with higher levels of antioxidants and beneficial fatty acids such as conjugated linoleic acid (CLA) and omega-three fatty acids, according to research findings from Newcastle University in the United Kingdom. Part of the ongoing cross-European Quality Low Input Food project, the study involved 25 farms across the United Kingdom and looked at three different farming systems: conventional high input, organically certified, and non-organic sustainable (low-input).Source: Journal of Science of Food and Agriculture, online (2008).

A three-year study in the United Kingdom, sponsored by the Organic Milk Suppliers’ Co-operative, found organic milk contained 68 percent more omega-3 fatty acids, on average, than conventional milk. The study was conducted independently by the Universities of Liverpool and Glasgow during 2002 and 2005 centering on a cross-section of UK farms over a 12-month production cycle.Source: “Comparing the fatty acid composition of organic and conventional milk,” Ellis, K., Innocent, G., Grover-White, D., Cripps, P., McLean, W.G., Howard, C.V. & Mihm, M., Journal of Dairy Science, 89: 1938-1950 (2006).

A European research team led by Swiss scientist Lukas Rist has found that mothers consuming mostly organic milk and meat products have about 50 percent higher levels of rumenic acid, a conjugated linoleic acid, in their breast milk.Source: June 2007 British Journal of Nutrition.

Featured Chef Ann Cooper

In this interview, Chef Ann Cooper explains why she thinks organic is worth it in schools and offers tips on how to make better food in schools a reality.